Most cases of ALS are sporadic; however, ~10% of cases are familial and follow an autosomal-dominant pattern of inheritance [167,168]—of these, 20% are caused by mutations in the Cu/Zn superoxide dismutase (SOD1) gene, resulting in a toxic gain-of-function via a currently unknown mechanism [169,170,171]. This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.